Sensor system for a positive displacement pump

ABSTRACT

A positive displacement pump is provided that includes a pump housing having a pump chamber; a plunger mounted in the pump housing for reciprocating motion in the pump chamber; a suction valve positioned to allow a fluid to enter the pump chamber upon movement of the plunger in a first direction; a discharge valve positioned to discharge the fluid from the pump chamber upon movement of the plunger in a second direction; and at least one sensor enclosed by the pump housing for measuring at least one pump condition parameter.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to and is a Continuation-In-Part ofU.S. patent application Ser. No. 11/312,124, filed on Dec. 20, 2005,which is incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates generally to a sensor system for use in apositive displacement pump, and more particularly to such a sensorsystem mounted within the positive displacement pump.

BACKGROUND

Generally, positive displacement pumps, sometimes referred to asreciprocating pumps, are used to pump fluids in a variety of wellapplications. For example, a reciprocating pump may be deployed to pumpfluid into a wellbore and the surrounding reservoir. The reciprocatingpump is powered by a rotating crankshaft which imparts reciprocatingmotion to the pump. This reciprocating motion is converted to a pumpingaction for producing the desired fluid.

A given reciprocating pump may include one or more pump chambers thateach receive a reciprocating plunger. As the plunger is moved in onedirection by the rotating crankshaft, fluid is drawn into the pumpchamber through a one-way suction valve. Upon reversal of the plungermotion, the suction valve is closed and the fluid is forced outwardlythrough a discharge valve. The continued reciprocation of the plungercontinues the process of drawing fluid into the pump and dischargingfluid from the pump. The discharged fluid can be routed through tubingto a desired location, such as into a wellbore.

As is often the case with large systems and industrial equipment,regular monitoring and maintenance of positive displacement pumps may besought to help ensure uptime and increase efficiency. Accordingly, aneed exist for an improved monitoring system for a positive displacementpump.

SUMMARY

In one embodiment, the present invention is a positive displacement pumpthat includes a pump housing having a pump chamber; a plunger mounted inthe pump housing for reciprocating motion in the pump chamber; a suctionvalve positioned to allow a fluid to enter the pump chamber uponmovement of the plunger in a first direction; a discharge valvepositioned to discharge the fluid from the pump chamber upon movement ofthe plunger in a second direction; and at least one sensor enclosed bythe pump housing for measuring at least one pump condition parameter.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features and advantages of the present invention will bebetter understood by reference to the following detailed descriptionwhen considered in conjunction with the accompanying drawings wherein:

FIG. 1 is a schematic illustration of a pumping system for use in a welloperation according to one embodiment of the present invention;

FIG. 2 is a schematic illustration of a various sensors coupled to acontrol system for use in the pumping system of FIG. 1;

FIG. 3 is a cross-sectional view of a positive displacement pump thatcan be used in the system illustrated in FIG. 1, according to anembodiment of the present invention;

FIG. 4 is close up view taken from detail 4 of FIG. 3, showing theinteraction of a valve with a valve seat; and

FIG. 5 is close up view of the valve and valve seat of FIG. 4 shown withdegradation of both the valve and the valve seat.

DETAILED DESCRIPTION

In the following description, numerous details are set forth to providean understanding of the present invention. However, it will beunderstood by those of ordinary skill in the art that the presentinvention may be practiced without these details and that numerousvariations or modifications from the described embodiments may bepossible.

As such in FIGS. 1-5 embodiments of the present invention relate to asystem and methodology for providing optimal use of a positivedisplacement pump deployed, for example, in a well related system. Inone aspect, a sensor system is located within the positive displacementpump to detect vital pump condition parameters. These parameters can betransferred to a control system at the surface of the well, which caninterpret the parameters and determine the pump's condition. Thiscontrol system can also predict when maintenance or part replacementsare needed.

In one embodiment, the sensor system includes one or more sensors thatare self powered using the pump motion, the pump vibration, or anotherappropriate energy source from the pump, as a power source. As usedherein, a self-powered device is a device powered by a means other thana battery or an external power cord. For example, a self poweringmechanism of a sensor according to the present invention may include amagnet-coil assembly or a piezoelectric material, among otherappropriate self powering mechanisms.

In one embodiment described herein, the sensor system is used to obtaindata on pump condition parameters that indicate abnormal events duringpumping or degradation of suction valves and/or discharge valves withinthe pump. The determination of valve wear can be indicative of a failuremode, and the data can be used in predicting failure of the component.Examples of abnormal events that occur during pumping include pumpcavitation, loss of prime, valves stuck in an open or closed position,and debris interfering with valve closure.

Referring generally to FIG. 1, a system 20 is illustrated for use in awell application, according to one embodiment of the present invention.It should be noted that the present system and method can be used in avariety of applications. As such, the illustrated well application ismerely used as an example to facilitate explanation. In the illustratedembodiment, the system 20 includes, for example, a positive displacementpump, i.e. a reciprocating pump 22, deployed for pumping a fluid into awell 24 having a wellbore 26 drilled into a reservoir 28 containingdesirable fluids, such as hydrocarbon based fluids.

In many applications, the wellbore 26 is lined with a wellbore casing 30having perforations 32 through which fluids can flow between thewellbore 26 and the reservoir 28. The reciprocating pump 22 may belocated at a surface location 34, such as on a truck or other vehicle35, to pump fluid into the wellbore 26 through the tubing 36 and outinto the reservoir 28 through the perforations 32. By way of example,the well application may include pumping a well stimulation fluid intothe reservoir 28 during a well stimulation operation, e.g. pumping afracturing fluid into the well.

In the embodiment illustrated in FIG. 1, the positive displacement pump22 is coupled to a control system 40 by one or more communication lines42. The communication line(s) 42 can be used to carry signals betweenthe positive displacement pump 22 and the control system 40. Forexample, data from sensors located within the pump 22 can be outputthrough communication lines 42 for processing by control system 40. Theform of communication lines 42 may vary depending on the design of thecommunication system. For example, the communication system may beformed as a hardwired system in which communication lines 42 areelectrical and/or fiber-optic lines.

Alternatively, the communication system may include a wireless system inwhich communication lines 42 are wireless and able to provide wirelesscommunication of signals between the pump sensors and the control system40. An advantage of the wireless communication system is that it lackswires, which if present could be inadvertently moved and/or dislodgedfrom a desired location due to human interaction or due to movements orvibrations caused by the mere operation of the pump.

Referring to FIG. 2, the control system 40 may be a processor basedcontrol system able to process data received from a sensor system 44deployed within the pump 22. By way of example, the control system 40may be a computer-based system having a central processing unit (CPU)46. In one embodiment, the CPU 46 is operatively coupled to a memorydevice 48, as well as an input device and an output device 52. The inputdevice 50 may include a variety of devices, such as a keyboard, a mouse,a voice-recognition unit, a touch-screen, among other input devices, orcombinations of such devices. The output device 52 may include a visualand/or audio output device, such as a monitor having a graphical userinterface. Additionally, the processing may be done on a single deviceor multiple devices at the well location, away from the well location,or with some devices located at the well and other devices locatedremotely.

The sensor system 44 is designed to detect specific parametersassociated with the operation of the positive displacement pump 22. Datarelated to the specific parameters is output by the sensor system 44through communication line or lines 42 to the control system 40 forprocessing and evaluation (note again that in one embodiment thiscommunication is wireless.) The pump parameter data is used to determinepossible failure modes through indications of pump malfunctions, such aspump component degradations, e.g. pump valve or valve seat degradation.

The control system 40 also can be used to evaluate and predict anestimated time to failure using techniques, such as data regression. Aswill be explained more fully below, the sensor system 44 may include oneor more sensors located within the positive displacement pump 22.Examples of such sensors include a pump chamber sensor 54, a plungersensor 55, a pump housing sensor 56, a valve insert sensor 57, and avalve seat sensor 58.

A positive displacement pump 22 according to one embodiment of thepresent invention is illustrated in FIG. 3. As illustrated, the pump 22includes a pump housing 62 having a pump chamber 64. A plunger 66 isslidably mounted within pump housing 62 for reciprocating motion withinthe pump chamber 64. The reciprocating motion of the plunger 66 acts tochange the volume of the pump chamber 64. The pump 22 further includescheck valves, such as a suction valve 68 and a discharge valve 70, thatcontrol the flow of fluid into and out of the pump chamber 64 as theplunger 66 reciprocates.

The reciprocating motion of the plunger 66 may be generated by arotating crankshaft (not shown), as known to those of ordinary skill inthe art. It should also be noted that a single plunger and a single pumpchamber are illustrated to facilitate explanation. However, theillustrated single plunger and single pump chamber also arerepresentative of potential additional plungers and pump chambers alongwith their associated check valves. For example, the illustrated singleplunger and single pump chamber may form a portion of a three chamber,triplex pump. With a triplex pump or other multiple chamber pumps, themotion of the plungers can be staggered to achieve a more uniform flowof pumped fluids, making such pumps desirable in a number of pumpingapplications.

The suction valve 68 and the discharge valve 70 are actuated by fluidand spring forces. The suction valve 68, for example, is biased toward asuction valve seat 72, i.e. toward a closed position, by a spring 74positioned between the suction valve 68 and a spring stop 76. Similarly,the discharge valve 70 is biased toward a discharge valve seat 78, i.e.toward a closed position, by a discharge valve spring 80 positionedbetween the discharge valve 70 and a spring stop 82.

As shown, the suction valve 68 further includes a sealing surface 84oriented for sealing engagement with the valve seat 72. The sealingsurface 84 of the valve 68 includes a strike face 86, that may be formedof a metal, and a flexible portion that may be formed as a flexiblevalve insert 88. The flexible valve insert 88 may be slightly raisedrelative to the strike face 86.

Similarly, the discharge valve 70 includes a sealing surface 90 orientedfor sealing engagement with the valve seat 78. The sealing surface 90 ofthe valve 70 includes a strike face 92, that may be formed of a metal,and a flexible portion that may be formed as a flexible valve insert 94.The flexible valve insert 94 may be slightly raised relative to strikeface 92.

When the plunger 66 moves outwardly (to the left in FIG. 3), a drop inpressure is created within the pump chamber 64. This drop in pressurecauses the suction valve to move against the bias of spring 74 to anopen position and causes fluid to flow into pump chamber 64 through thesuction valve 68. This phase can be referred to as the “suction stroke.”When the plunger 66 moves in a reverse direction (to the right in FIG.3), the suction valve 68 is closed by the spring 74, and pressure isincreased in the pump chamber 64. The increase in pressure causes thedischarge valve 70 to open and forces fluid from the pump chamber 64outwardly through discharge valve 70. The discharge valve 70 remainsopen while the plunger 66 continues to apply pressure to the fluid inthe pump chamber 64. The high-pressure phase in which fluid isdischarged through the discharge valve 70 is known as the “dischargestroke.”

As each valve 68,70 is closed, its valve insert 88,94 contacts itscorresponding seat 72,78 and is compressed until the strike face 86,92of the valve 68,70 also makes contact with the seat 72,78. With thesuction valve 68, for example, the valve insert 88 is compressed againstthe valve seat 72 until the strike face 86 contacts the valve seat 72.This normally occurs shortly after initiation of the discharge stroke.With the discharge valve 70, the valve insert 94 is compressed againstthe valve seat 78 until the strike face 92 contacts the valve seat 78.This normally occurs shortly after initiation of the suction stroke.

The flexible valve inserts 88,94 are beneficial for environments inwhich fluid containing an abrasive material, such as sand, or otherparticulates is pumped. Typically, the valve inserts 88,94 are composedof urethane or some other conventional deformable polymer. Thedeformation of the flexible valve inserts 88,94 enables the valves 68,70to seal even when fluids containing particles, for example cementparticles, sand or proppant, are moved through the pump 22. However, theabrasive action of such particulates during extended use of the valves68,70 causes the flexible valve inserts 88,94 to degrade, which reducesthe ability of the valves 68,70 to form a seal and ultimately leads tovalve failure and pump malfunction. In one embodiment, the valve inserts88,94 are made of urethane or another conventional polymers.

However, the valve inserts 88,94 may not be necessary in applicationsinvolving the pumping of relatively “clean” or “non-abrasive” fluids. Insuch applications, the sealing surfaces 84,90 of the valves 68,70 can beformed without the valve inserts 88,94 such that sealing is accomplishedonly between the metal strike face 86,92 of the valves 68,70 and thevalve seats 72,78. In embodiments where the valves 68,70 are designedwithout the flexible valve inserts 88,94, the metal strike faces 86,92of the valves 68,70 may still degrade with repeated use, althoughtypically not as quickly.

As such, the sensor system 44 is incorporated into the pump 22 to detectpump condition parameters which can be used to determine component wearor degradation, and/or other pump malfunctions. In one embodiment, thesensor system 44 is used to detect wear on the suction and/or dischargevalves 68,70 through the use of sensors positioned at various locationswithin the positive displacement pump 22.

For example, in one embodiment the sensor system 44 includes a pumpchamber sensor 54 mounted on a face of the plunger 66 at a positionadjacent to the pump chamber 64 to allow for continued exposure of thesensor 54 to the pump chamber 64 and the fluid disposed therein. At sucha position, the sensor 54 may measure the pump chamber pressure,temperature and/or vibration, among other desired parameters. Such asensor 54 may be self powered using energy from the motion of theplunger 66. The pump chamber sensor 54 may include any appropriatesensor, such as a pressure sensor, a temperature sensor, or anaccelerometer, among other appropriate sensors.

The sensor system 44 may include a plunger sensor 55 mounted on orinside the plunger 66. At such a position, the plunger sensor 55 maymeasure the position of the plunger 66, among other desired parameters.Such a plunger sensor 55 may be self powered using energy from themotion of the plunger 66. The plunger sensor 55 may include anyappropriate sensor, such as an accelerometer or a proximity switch,among other appropriate sensors.

The sensor system 44 may include a pump housing sensor mounted on orwithin an interior wall of the pump housing 62. Although FIG. 3 showstwo possible locations of the pump housing sensor 56, in one embodimentthe pump housing sensor 56 may be mounted at any position along theinterior wall of the pump housing 62 as long as it is adjacent to thepump chamber 64. The pump housing sensor may measure the pump chamberpressure, temperature and/or vibration, among other desired parameters.

Note that in order to measure the pump chamber pressure, it isadvantageous for the pump housing sensor 56 to be positioned such thatit may contact fluid within the pump chamber 64. The pump housing sensor56 may be self powered using stress from the energized fluid within thepump chamber 60. The pump housing sensor 56 may include any appropriatesensor, such as a pressure sensor, a temperature sensor, or anaccelerometer among other appropriate sensors.

As shown in FIGS. 4 and 5, the sensor system 44 may include a valveinsert sensor 57 mounted on or within the flexible valve inserts 88,94of either or both of the valves 68,70. The valve insert sensor 57measures a degradation 25 (see FIG. 5) or a wearing away of the valveinsert 88,94 to which it is attached.

Typically, the valve insert 88,94 is composed of an insulator, and thevalve seat 72,78 is composed of a conductor. In such an embodiment, thevalve insert sensor may be a sensor that measures conductivity betweenitself and another conductor, such as an electrical resistivity sensoror a voltage sensor, among other appropriate sensors.

As such, in this embodiment, the valve insert sensor 57 is embedded inthe valve insert 88,94 at a position such that when the valve insert88,94 is not degraded (as shown in FIG. 4) or at least when the valveinsert 88,94 is degraded to an acceptable level, the valve insert sensor57 does not contact the valve seat 72,78 and therefore cannot measure aconductivity therebetween; and when the valve insert 88,94 is degradedto an undesirable level (as shown in FIG. 5 and indicated by degradedsection 25), the valve insert sensor 57 contacts the valve seat 72,78and measures a conductivity therebetween. At such a time, the valveinsert sensor 57 may send a signal to the control system 40 indicatingan undesirably worn valve insert 88,94.

Additionally or in the alternative, the valve insert sensor 57 may beconfigured to measure a conductivity between itself and the fluid beingpumped. Such a situation occurs when the end of the sensor 57 is exposedand in contact with the fluid being pumped, but not yet exposed to theextend allowing the sensor 57 to contact the valve seat 72,78.

In another embodiment, the valve insert sensor 57 measures the integrityof itself. When the integrity is damaged to a predetermined condition,then the control system 40 determines that the valve insert 88,94 isundesirably worn. In either embodiment, the valve insert sensor 57 canbe self powered by the stress from the valve insert 88,94 deformation.

As is also shown in FIGS. 4 and 5, the sensor system 44 may include avalve seat sensor 58 mounted on or within the valves seat 72,78. Thevalve seat sensor 58 measures a degradation 27 (see FIG. 5) or a wearingaway of the valve seat 72,78 to which it is attached.

Typically, the valve seat 72,78 is composed of a conductor, and thestrike face 86,92 of the valve 68,70 is composed of a conductor. In suchan embodiment, the valve seat sensor 58 may be a sensor that measuresconductivity between itself and another conductor, such as an electricalresistivity sensor or a voltage sensor, among other appropriate sensors.

As such, in this embodiment, the valve seat sensor 58 is encased, atleast partially, in an insulator 59; and the sensor 58 and the insulator59 are embedded in the valve seat 72,78 at a position such that when thevalve seat 72,78 is not degraded (as shown in FIG. 4) or at least whenthe valve seat 72,78 is degraded to an acceptable level, the valve seatsensor 58 does not contact the strike face 86,92 of the valve 68,70 andtherefore cannot measure a conductivity therebetween; and when the valveseat 72,78 is degraded to an undesirable level (as shown in FIG. 5 andindicated by degraded section 27), which is quickly followed by adegradation of the insulator 59, the valve seat sensor 58 contacts thevalve seat 72,78 and measures a conductivity therebetween. At such time,the valve seat sensor 58 may send a signal to the control system 40indicating an undesirably worn valve seat 72,78.

Additionally or in the alternative, the valve seat sensor 58 may beconfigured to measure a conductivity between itself and the fluid beingpumped. Such a situation occurs when the end of the sensor 58 is exposedand in contact with the fluid being pumped, but not yet exposed to theextend allowing the sensor 58 to contact the strike face 86,92 of thevalve 68,70.

In another embodiment, the valve seat sensor 58 measures the integrityof itself. When the integrity is damaged to a predetermined condition,then the control system 40 determines that the valve insert 88,94 isundesirably worn. In either embodiment, the valve seat sensor 58 can beself powered by the stress from the valve seat 72,78 deformation, or thevalve seat sensor 58 can be battery powered and operated in alow-bandwidth mode.

Any one or all of the sensors 54-58 may be mounted within the pumphousing 62 (FIG. 3 shows each of the sensors 54-58 mounted within thepump housing 62) to protect the sensors 54-58 from the environmentexternal to the pump housing 62 and to protect the sensors 54-58 frominadvertent movement or dislodgement of the sensors 54-58, such as byinadvertent human contact.

As eluded to above, any one or all of the sensors 54-58 may communicatewith the control system 40 wirelessly. Wireless communication betweenthe sensors 54-58 and the control system 40 lessens the likelihood ofthe sensors 54-58 being inadvertently moved and/or dislodged from adesired location due to inadvertently human contact or due to movementsor vibrations caused by the mere operation of the pump 22.

As described above, a plurality of pump parameters detected within apositive displacement pump can be used individually or in combination todetermine indications of pump component degradation. It should be notedthat different types of sensors can be used in pump 22, and thosesensors can be located at a variety of locations within the pumpdepending on, for example, pump design, well environment and sensorcapability. Additionally, the sensor or sensors may be deployed in pumpshaving a single pump chamber or in pumps having a plurality of pumpchambers to provide data for determining degradation of valvesassociated with each pump chamber and/or other pump malfunctions. Notethat the sensors 54-58 are shown schematically in FIGS. 1-5 and are notnecessarily drawn to scale.

The preceding description has been presented with reference to presentlypreferred embodiments of the invention. Persons skilled in the art andtechnology to which this invention pertains will appreciate thatalterations and changes in the described structures and methods ofoperation can be practiced without meaningfully departing from theprinciple, and scope of this invention. Accordingly, the foregoingdescription should not be read as pertaining only to the precisestructures described and shown in the accompanying drawings, but rathershould be read as consistent with and as support for the followingclaims, which are to have their fullest and fairest scope.

What is claimed is: 1.-31. (canceled)
 32. A method of optimizingoperation of a pump used in a well application, comprising: positioninga positive displacement pump at a well site; operating the positivedisplacement pump; detecting a plurality of parameters within thepositive displacement pump that can be used to indicate pump wear; andpredicting a component failure based on changes in the plurality ofparameters.
 33. The method as recited in claim 32, wherein detectingcomprises detecting parameters indicative of valve wear within thepositive displacement pump.
 34. The method as recited in claim 32,further comprising outputting data from a sensor system, positioned todetect the plurality of parameters, to a control system.
 35. The methodas recited in claim 34, wherein the control system automaticallydetermines the occurrence of component wear based on changes in at leastone of the detected parameters.
 36. The method as recited in claim 32,wherein detecting comprises detecting a pump chamber pressure, a pumpplunger position, and a valve closing.
 37. The method as recited inclaim 36, wherein the positive displacement pump further comprises aplurality of sensors for detecting the plurality of parameters.
 38. Themethod as recited in claim 37, wherein the plurality of sensorscomprises a pressure sensor mounted to sense pressure in a pump chamberof the positive displacement pump.
 39. The method as recited in claim37, wherein the plurality of sensors comprises a discharge pressuresensor.
 40. The method as recited in claim 37, wherein the positivedisplacement pump comprises a plunger, and the plurality of sensorscomprises a position sensor to detect the position of the plunger. 41.The method as recited in claim 37, wherein the positive displacementpump comprises a suction valve and a discharge valve, and the pluralityof sensors comprises at least one accelerometer to detect closing of atleast one of the suction valve and the discharge valve.
 42. The methodas recited in claim 41, further comprising outputting data from theplurality of sensors to a control system that processes the data todetermine any parameter timing changes indicative of future failure ofthe suction valve and the discharge valve.
 43. The method as recited inclaim 41, further comprising outputting data from the plurality ofsensors to a control system that processes the data to determine anychanges in rising and falling slopes of a pump chamber pressure waveformindicative of future failure of the suction valve and the dischargevalve.
 44. The method as recited in claim 41, further comprisingoutputting data from the plurality of sensors to a control system thatprocesses the data to perform frequency spectrum analyses on anaccelerometer signal to determine changes in the frequency spectrum overtime.